Electrical three-part,keylocked switch



July 1, 1969 s.|-|. SUBER ELECTRICAL THREE-PART, KEY-LOCKED SWITCH Filed Jan. 16, 1968 INVENTOR.

STEPHEN SUBER ATTORNEYS US. Cl. 20044 4 Claims ABSTRACT OF THE DISCLOSURE An elongated key, with two integral blade elements at an angle to each other in a V-shaped cross-section, is adapted to be inserted in .a V-shaped key hole in a cylindrical rotary key housing and into connection with a hemispherical-shaped rotary cam element within the outer casing. Two tapered prongs, extending one from each blade element, are provided for engaging complementary spaced openings in the circular flat face of the cam element to rotate it. The cam element rotates independently of the key housing on a short stub shaft mounted in the bottom of the casing. The cam is provided with a variable-radius or curved portion which moves an operating arm for a micro switch or the like as the cam is rotated by the key.

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

The present invention relates to electrical key-locked switches and the like, and more particularly to electrical key-locked switches for electrical shop tools and appliances which may be used by authorized persons and which are adapted to prevent the unauthorized use thereof by others.

In many establishments where many persons have excess to electrical equipment, such as large home appliances in apartment houses and the like, or small and large electrically-operated machine tools in manufac turing plants, it is desirable to provide locking means therefor to prevent the unauthorized use of such equipment. It is often difficult, after an appliance is constructed, to add a switch or control means thereto without getting into the interior thereof.

It is, therefore, an object of the present invention to provide an improved locking control with a high degree of protective power in connection with the electrical supply cord or connection means for equipment of the type referred to and in which the locking means is adapted for preventing easy access to the switch component thereof or its easy operation by other than a normal key means as provided.

It is a further object of this invention to provide an improved electrical key-locked switch for electrical appliances and equipment which will effectively prevent unauthorized use thereof while being of simplified, lowcost construction.

It is also an object of this invention to provide improved electrical key locked switch which is adapted to be provided in connection with all-type plugs and control boxes for electrical equipment.

In accordance with one embodiment of the invention, a protective outer casing or box is provided for the switch and adapted for wall mounting or for mounting on the end of a supply cord as may be desired. The casing or box may be of metal or other hard protective material which is adapted to prevent entry therein without the use of cutting tools or the like. The key-locked switch of the present invention is in three parts and includes a cylindrical rotary-key housing, a hemispherical- United States Patent 3,453,402 Patented July 1, 1969 shaped rotary ca-m element having a circular flat face or top, .and a switch having an operating arm which engages the cam element. These three parts are all aligned substantially on a common axis, which is the axis of rotation of the cylindrical key housing. The key housing rotates in a sleeve or burning element which is rigidly mounted in and fixed to the outer casing wall and extends interiorly thereof. The key housing is held to rotate in the sleeve by suitable groove-and-ball locking means interconnecting the sleeve with the key housing.

Directly in axial extension of the key housing is a stub-guide shaft on which the cam element is mounted to rotate, with the flat surface thereof normal to the axis of the shaft. Like the key housing, the cam is provided with a groove adjacent to the flat face or top thereof and extending circumferentially around the cam element a predetermined angular distance. A ball stop element for the groove prevents the turning of the cam more than a predetermined distance, such as An elongated trough-shaped key is fitted to a V-shaped key hole in the key housing and is adapted to extend longitudinally therethrough and into communication with the flat face of the cam element. The key is effectively an elongated double bladed type, having two integral blade elements and at an angle to each other and provided with a flat key head at one end joined to both blade elements. At the opposite end of the key two spaced substantially-parallel tapered prongs are provided in prolongation thereof and adapted to enter correspondinglyspaced locking recesses or openings in the flat face of the cam element. In this way, as the key is inserted through the key housing it first passes through the key housing in the V-shaped key hole and then the forward or inner end of the two blades, which .are tapered and prong-shaped, enter the corresponding openings in the cam for turning the cam simultaneously with the key and the key housing. This rotates the cam about the axis provided by the guide shaft and between the limits of the stop elements provided thereon, and thus controls the switch through its operating arm in contact with the cam.

A variable-radius cam surface is provided in the hemispherical lower portion of the cam which moves a point of contact to one side of the center in a longitudinal direction with respect to the axis of the key. This point of contact in turn operates the switch arm for a suitable electric switch which may be contained within the outer casing. In a preferred embodiment, this switch is a microswitch having the lever arm thereof in contact with the cam surface and to one side of the center thereof. The cam surface is on a variable radius, or curved high on that side, to operate the switch as the cam is rotated by the key to turn the switch OFF and ON, as the case may be.

The invention will further be understood from the following description, when considered with reference to the accompanying drawing, and its scope is pointed out in the appended claims.

In the drawing, FIG. 1 is a side view, in elevation, of a three-part key locked switch in accordance with the invention, with a portion of the outer casing broken away to show the interior arrangement thereof,

FIG. 2 is a similar view of the switch of FIG. 1, showing the interior portions thereof with a locking key in place for operation thereof, in accordance with the invention, and

FIG. 3 is a further elevational view, in perspective, of the switch of FIG. 1 showing its mounting and use as part of a plug connector for electrical equipment.

Referring to the drawings, wherein like parts throughout the various figures are designated by like reference numerals, and referring particularly to FIGS. 1 and 2,

a rectangular outer switch casing or box 5 adapted for wall mounting, or the like, is provided with an opening in one wall thereof for receiving a cylindrical outer sleeve or bearing element 6 which depends therein and is supported by an outer collar 7 as part thereof. The box 5 provides a protective housing on casing for the switch and serves as a mounting means therefor whereever it is desired to use the switch.

An upper or outer cylindrical rotary lock element'8 is mounted to rotate in the outer sleeve 6 with its upper or outer end exposed, as shown in FIG. 1. The rotary lock element 8 is coaxial with the sleeve or bearing element 6 and is held in place and limited in rotational movement by a ball stop element 9 which operates in a stop groove 10 within the sleeve 6. The stop groove 10 extends only part way around the periphery of the sleeve 10 and thereby prevents rotation of the lock element 8 beyond a predetermined limit which is substantially a quarter turn for example.

A V-shaped central key hole or key slot 12 extends longitudinally through the rotary lock element 8 for receiving a correspondingly-shaped elongated double bladed key 14 which is used to operate the switch. The key comprises two blades 15 which are integral or in one piece and are at an angle to each other such as 90 or greater. The key is provided with a flat key head 16 at its outer end joined to both blade elements.

Two spaced substantially-parallel tapered key prongs 17 are carried by and are integral with the inner end of the key, one prong extending from and in prolongation of each blade element. The upper or outer cylindrical rotary lock element is the first part of the three-part keylocked switch. The second part is an intermediate or inner hermispherical-shaped rotary cam element 19 having a circular fiat face or top 20 in which are located two spaced locking recesses or openings 21 for receiving the key prongs 17, as indicated in FIG. 2 for example. The rotary cam element 19 also is provided with a variable-radius outer or bottom cam surface 22, This is adapted to move a point of contact with a switch operating arm 24 of a micro-switch or like switch element 25 to move it and operate the switch button 26 to close or open the switch as the case may be. The switch element 25 is the third part of the three-part key lock switch and is the electrical operating element thereof. The two preceding parts 8 and 19 are deposed in alignment therewith on the comrnon axis of the lock element and cam element. The switch operating arm contact with the cam is thus high at one point to operate the switch.

The switch 25 is mounted in the bottom of the box or protective outer casing 5 and also mounted thereon is a supporting shaft or stud 28 for the cam element 19. This also lies on the axis of rotation of the cam as indicated in both figures. It is thus in prolongation of the axis of the lock element 8 which extends to one side of the switch 25. The shaft 28 has a smooth running fit in the cam element 19 so that the latter is free to rotate thereon in a position maintained in alignment with the key element 8. The cam element 19 is prevented from full 360 rotation by a stop means similar to that for the key ele ment 8. Thus it may be provided by two detent ball or pin elements on diametrically opposite sides thereof adjacent to the top, as indicated at 29, and these detents are in turn supported in position or in place on opposite sides of the cam element by supporting brackets 30 secured to the inner wall of the box or integral therewith. The detent pins 29 are in engagement each with a peripheral groove 31 in the cam element 19 adjacent to the flat top 20 and this groove extends part way around the cam so that the cam is limited to substantially a 90 rotational movement, like the key element 8.

The switch is provided with terminals 32 one of which appears in FIG. 1 and these are connected with the electrical leads 33 for the switch and which extend through a cable 34 to the exterior thereof as indicated by the covered conductors 35 within the cable 34. These conductors may be connected to control any suitable appliance or device, not shown, for applying the power thereto when it is desired to operate. Thus the switch 25 may be considered normally to be in the open position as shown in FIGS. 1 and 2 and to be closed when the lever arm 24 strikes the button 26 by rotation of the cam 19.

Both the key rotary lock element 8 and the cam element 19 are adapted to turn independently one of the other so that the key 14 must first be inserted into the V-shaped opening 12 and push down through the element 8 into engagement with the flat top 20 of the cam element 19. The key is then turned until the prongs 17 engage the recesses 21 and permit both the cam element 19 and the key lock element 8 to rotate together by rotation of the key 14. This is turned until the cam surfaces 22 moves the switch lever to operate the switch as desired. Thus rotation of the key element 8 alone will not serve to operate the switch since, without the key, there is no con nection between it and the cam 19 at the time. Not only must the key fit the V-shaped groove but it must also have the prongs spaced the proper distance apart to enter the small recesses or openings 21. Thus the key locked switch of the present example is substantially fool proof, which being of a simplified construction that is affective to prevent operation of the protective apparatus by unauthorized persons.

Referring to FIG. 3 it will be seen that this switch may be used also in an attachment plug for an apparatus directly at at the plug prongs to prevent its unauthorized use. The construction here is also such that the apparatus may not be connected without considerable reworking of the wiring or the connections thereto. In this embodiment, the three operative switch parts, comprising the rotary lock element 8, the rotary cam element 19 and the cam operated switch 25 are mounted in the same relation as shown in FIGS. 1 and 2 within a plug body or casing 35 of metal or relatively hard material. This is provided with forward end prongs 36 and 37 for plugging into a wall outlet and also is provided with a ground plug terminal 38 mounted in and connected with the casing and bracket element 30 on the interior of the plug body or casing as shown in FIG. 3. Two connection leads 39 and 40 are connected respectively with the screw terminals 41 and 42 of the prong blades 36 within the casing as shown. The lead 39 is connected directly with one of the leads 35 while the lead 40 is connected through with the other of the leads 35 within the casing.

The current from the prongs 36 and 37 is thus controlled by the switch in its flow through to output leads 35 for any apparatus to be connected therewith. A ground conductor 45 may be provided within the cable 34 and is connected to the casing inside of the plug body 35 and preferably to the outer brackets 30 as shown in FIGS. 1 and 2. It will be noted herein that the cable 34 is provided with an outer metallic armor 46 which is of the flexible type commonly used for this purpose to prevent damage to the wiring and also, in this case, to prevent tampering with the connection leads. This armor outer metallic cov ering enters the casing 35 and is secured therein so that it cannot be pulled out.

With this arrangement the key is inserted in the slot 12 in the same manner as described for FIGS. 1 and 2 and is turned to control the switch to disconnect the input terminals 36 and 37 from the outgoing leads 35 whenever it is desired to lock ofI equipment controlled by the plug. Thus an armored two-wire apparatus plug and cord connection may be provided in accordance with the invention or the control switch may be placed in a protective box mounting for use on a wall as is desired. In either case the simple twopart drive for the three-part switch embodies a simple rotary element carried by a suitable sleeve and a cam having corresponding openings for receiving the key and having a cam surface directly below. Thus it can be made in the form of a hemisphere and easily manufactured and assembled with the cylindrical lock element and its cylindrical outer sleeve or bearing element within any suitable container.

I claim:

1. An electrical three-part key-locked switch comprising in combination,

an outer protective switch casing having a circular opening through one wall thereof,

a cylindrical outersleeve providing a fixed bearing element mounted in said wall of the casing and depending therein from a terminal collar engaging said opening,

an outer cylindrical rotary lock element adapted to be key operated and mounted to rotate in said outer sleeve and bearing element coaxially therewith,

means for holding said lock element within said sleeve element comprising a ball stop carried by said lock element and a stop groove in said sleeve element extending around said lock element less than a full rotational turn thereof,

means providing a V-shaped central key slot extending longitudinally through said rotary lock element,

an elongated key for said key slot having two blades integral and at an angle to each other to fit said slot,

means integral with and carried by the inner end of said key providing two spaced key prongs one extending from and in prolongation of each blade,

an intermediate inner hemispherical-shaped rotary cam element having a circular fiat top face with two spaced locking recesses located therein for receiving said key prongs,

means providing a variable-radius bottom cam surface on said cam element having a movable switch-operating point of contact thereon,

a switch operating arm in contact with said point to be moved thereby, and

a lower switch element connected to be operated by said arm in response to movement thereof with said point of contact on said cam.

2. An electrical three-part key-locked switch as defined in claim 1, where in the cam is provided with a central guidance shaft extending therethrough and connected with said casing, and wherein said cam is provided with a ball-stop-and-groove stop means for limiting the movement thereof to less than a full revolution in a rotational direction only and against longitudinal movement.

3. An electrical three-part key-locked switch as defined in claim 1, wherein the outer protective casing is a plug body having extended terminal prongs and having an armored outlet cord connection means therewith for an apparatus to be controlled by said switch.

4. An electrical three-part locking switch in combination,

an outer protective switch casing having a switch-operating opening in one wall thereof and a connection lead opening in a second wall thereof,

a cylindrical outer bearing element mounted in said comprising 6 switch-operating opening and depending into said casing,

said bearing element having an integral collar engaging said wall about said opening,

an outer cylindrical rotary lock element adapted to be key operated and mounted to rotate in said outer bearing element coaxially therewith and with one end thereof exposed externally of said casing for key operation,

ball-and-groove type means for holding said look element against longitudinal movement in said cylindrical outer bearing element and to a rotational movement less than a full rotational turn thereof.

means providing a V-shaped central key slot extending longitudinally through said rotary lock element from end to end,

an elongated double-bladed key for said key slot having two integral blade elements at an obtuse angle to each other and adapted to fit and extend through said key slot,

two spaced substantially-parallel tapered key prongs carried by said key one extending equally from and in prolongation of each blade element,

an intermediate hemispherical-shaped rotary cam element having a circular fiat face with two spaced locking recesses located therein and positioned for receiving and engaging said key prongs,

means providing a variable-radius in the hemispherical surface of said cam element to effect a longitudinally movable contact point thereon,

a switch operating arm in engagement with said point for movement thereby in response to rotation of said cam element,

a lower switch element connected to be operated by said arm in response to movement of said contact point, and

a central guidance shaft carried by the inner wall of the casing and extending through said cam centrally and normal to the plane of the fiat face thereof, and

ball-and-groove type stop means for limiting the rotational movement of said cam element to less than a fullfturn and against longitudinal movement of said sha t,

said last named means including two diametrially-opposed stop lugs extending from said inner casing wall on opposite sides of said cam element and having ball-stop elements thereon, and two peripherallyextending ball grooves in said cam element adjacent to said fiat face engaging said ball-stop elements.

References Cited UNITED STATES PATENTS 5/1948 Jacobi 200 14 X 8/ 1967 Canaday 200-44 

